An **IV cannula** is a medical device shaped as a narrow, hollow tube used to access veins. It is typically made from body-compatible materials such as polyurethane or Teflon, allowing it to enter veins smoothly without causing damage. The purpose of inserting an IV cannula is to administer medications, fluids, or blood directly into the bloodstream, or to collect blood samples. It is usually placed in veins of the hands, arms, or sometimes legs. The cannula tube is mounted on a thin needle (trocar) that is initially used to puncture the skin and vein; the needle is then removed, leaving the cannula in the vein.
Applications of an IV Cannula
- Administration of fluids, including IV fluids and electrolytes
- Blood and blood product transfusion
- Injection of various medications, from antibiotics to chemotherapy drugs
- Blood sampling for diagnostic tests
- Providing rapid venous access in emergency situations
- Intravenous nutrition or parenteral feeding
Types of IV Cannulas
IV cannulas are categorized based on type, insertion site, and application:
- Peripheral IV Cannula
The most common type, inserted into superficial veins of the hand or arm. Typically used for 72–96 hours and should be replaced regularly to prevent infection and inflammation. - Central Line
Used for access to larger central veins such as the jugular, subclavian, or femoral veins. Suitable for patients requiring long-term therapy and can remain in place for weeks or months. - Midline Cannula
A type between peripheral and central lines, generally used for treatments or infusions lasting more than 5 days up to about a month. - Winged Cannula (Butterfly Cannula)
Equipped with flexible wings on both sides for better stabilization on the skin, making it easier to handle and secure. - Ported Cannula
Features an additional port alongside the cannula tube, allowing extra injections without puncturing the vein again, reducing the risk of infection and pain.
IV Cannula Sizes and Color Coding
IV cannulas are manufactured in various sizes, chosen according to vein diameter and fluid flow rate. These sizes are identified by specific color codes, allowing quick and easy recognition.
| Gauge Number | Color | Common Use | Flow Rate (Liters/Hour) |
| 14G | Orange | Major surgeries, blood transfusion, emergency cases | Approx. 10.3 for blood |
| 16G | Gray | Surgery, fluid replacement, blood transfusion | Approx. 7.1 for blood |
| 18G | Green | Emergency cases, high-volume fluids, stem cell transplantation | 2.7 for blood |
| 20G | Yellow | Routine injections, medium-volume fluids | Lower rate than above |
| 22G | Blue | Adult patients, routine injections, sampling | Lower rate |
| 24G | Purple | Pediatric patients, thinnest cannula for children and sensitive patients | Lowest flow rate |
IV Cannula Insertion Procedure
- 1. Selecting the appropriate site for cannulation (usually superficial veins of the hand and forearm).
- 2. Disinfecting the site with alcohol or an antiseptic solution.
- 3. Using a trocar needle to insert the cannula into the vein.
- 4. Securing the cannula with adhesive tape and sometimes a bandage to prevent movement.
- 5. Connecting to a syringe or infusion equipment.
IV Cannula Care
- Keep the insertion site dry and clean.
- Avoid pulling or putting pressure on the cannula.
- Cover the cannula with waterproof plastic during bathing.
- Regularly inspect the insertion site for signs of inflammation or infection (redness, swelling, pain).
- Avoid excessive bending of the wrist or elbow near the insertion site.
- Replace the cannula every 3 to 4 days or as directed by a physician.
Possible Complications
- Infection at the cannula insertion site
- Pus formation and vein inflammation (phlebitis)
- Formation of blood clots at the cannula site
- Bleeding or blood leakage at the site
- Breaking or displacement of the cannula within the vein
Important Tips for Patients and Caregivers
- Never remove the cannula from the skin on your own.
- Inform a doctor or nurse if there is pain or swelling at the site.
- Report immediately if the bandage becomes loose or wet.
- Always maintain proper hand hygiene.
- Avoid heavy activities and frequent bending of the limb with the cannula.
Summary
An IV cannula is an essential and vital device for administering medications and fluids in hospitals and healthcare settings. Being informed about its types, applications, proper use, and care helps ensure patient safety and prevents complications. For medical equipment users and purchasers, understanding the technical specifications and differences among cannula types is a key guide to selecting the most suitable option for specific treatment needs.
